Light-emitting device, optical device, and information processing device comprising plural wiring members and circuit elements on side surfaces of a light emitting element array

ABSTRACT

A light-emitting device includes a wiring substrate, a base member provided on the wiring substrate, a light-emitting element array that has a first side surface and a second side surface facing each other, that has a third side surface and a fourth side surface facing each other and connecting the first side surface and the second side surface, and that is provided on the base member, a drive unit that is provided on the wiring substrate at a side of the first side surface and drives the light-emitting element array, a first circuit element that is provided on the base member at the side of the first side surface, a second circuit element that is provided on the base member at a side of the second side surface and has a larger occupation area on the base member than the first circuit element, and wiring members that are provided at a side of the third side surface and at a side of the fourth side surface and extend from an upper surface electrode of the light-emitting element array toward an outer side of the light-emitting element array.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of International Application No.PCT/JP2019/024550 filed on Jun. 20, 2019, and claims priority fromJapanese Patent Application No. 2019-053387 filed on Mar. 20, 2019.

BACKGROUND 1. Technical Field

The present invention relates to a light-emitting device, an opticaldevice, and an information processing device.

2. Related Art

JP-A-2018-54769 discloses an imaging device including a light source, alight diffusing member that includes plural lens provided adjacent toone another on a predetermined plane and that diffuses light emittedfrom the light source, and an image pickup device that receivesreflected light that is light diffused by the light diffusing member andreflected by a subject. The plural lenses are disposed such that aperiod of an interference pattern of the diffused light is three pixelsor less.

SUMMARY

When it is desired to reduce inductance of a circuit that drives alight-emitting element array, a wiring such as a bonding wire may beprovided not only at one side surface side of the light-emitting elementarray, but also at plural side surface sides. Further, plural circuitelements such as a light receiving element and a temperature detectingelement may need to be disposed close to the side surfaces of thelight-emitting element array. In such a case, a configuration isconceivable in which circuit elements are disposed on the base member ata side of the light-emitting element array close to a drive unit and onthe base member at a side opposite to the drive unit across thelight-emitting element array, and a wiring such as a bonding wire isprovided at the remaining side surface side. However, in a case wheresizes of the plural circuit elements are different from one another,when a larger circuit element is disposed at the side close to the driveunit, it is difficult to bring the drive unit and the light-emittingelement array close to each other, and inductance of the circuit mayincrease.

Aspects of certain non-limiting embodiments of the present disclosureovercome the above disadvantages and/or other disadvantages notdescribed above. However, aspects of the non-limiting embodiments arenot required to overcome the disadvantages described above, and aspectsof the non-limiting embodiments of the present disclosure may notovercome any of the disadvantages described above.

Aspects of non-limiting embodiments of the present disclosure relate toprovide a light-emitting device or the like having a structure in whichit is easy to bring a drive unit and a light-emitting element arrayclose to each other as compared with a structure in which a circuitelement having a large occupation area is provided at a side of thelight-emitting element array close to the drive unit.

Aspects of certain non-limiting embodiments of the present disclosureaddress the above advantages and/or other advantages not describedabove. However, aspects of the non-limiting embodiments are not requiredto address the advantages described above, and aspects of thenon-limiting embodiments of the present disclosure may not addressadvantages described above.

According to an aspect of the present disclosure, there is provided alight-emitting device including a wiring substrate, a base memberprovided on the wiring substrate, a light-emitting element array thathas a first side surface and a second side surface facing each other,that has a third side surface and a fourth side surface facing eachother and connecting the first side surface and the second side surface,and that is provided on the base member, a drive unit that is providedon the wiring substrate at a side of the first side surface and drivesthe light-emitting element array, a first circuit element that isprovided on the base member at the side of the first side surface, asecond circuit element that is provided on the base member at a side ofthe second side surface and has a larger occupation area on the basemember than the first circuit element, and wiring members that areprovided at a side of the third side surface and at a side of the fourthside surface and extend from an upper surface electrode of thelight-emitting element array toward an outer side of the light-emittingelement array.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the present invention will be described indetail based on the following figures, wherein:

FIG. 1 is a diagram showing an example of an information processingdevice;

FIG. 2 is a block diagram showing a configuration of the informationprocessing device;

FIG. 3 is a plan view showing a light-emitting element array;

FIG. 4 is a diagram showing a cross-sectional structure of one VCSEL inthe light-emitting element array;

FIGS. 5(a) and 5(b) are diagrams showing an example of a light diffusingmember, in which FIG. 5(a) is a plan view and FIG. 5(b) is across-sectional view taken along a line VB-VB in FIG. 5(a);

FIG. 6 is a diagram showing an example of an equivalent circuit thatdrives the light-emitting element array by low-side driving;

FIGS. 7(a) to 7(c) are diagrams showing a light-emitting device to whichthe present exemplary embodiment is applied, FIG. 7(a) is a plan view,FIG. 7(b) is a cross-sectional view taken along a line VIIB-VIIB in FIG.7(a), and FIG. 7(c) is a cross-sectional view taken along a lineVIIC-VIIC in FIG. 7(a);

FIGS. 8(a) to 8(c) are diagrams showing wiring patterns provided on awiring substrate and a base member, FIG. 8(a) shows a front surface ofthe wiring substrate, FIG. 8(b) shows a front surface of the basemember, and FIG. 8(c) shows a back surface of the base member; and

FIG. 9 is a plan view showing a light-emitting device for comparison towhich the present exemplary embodiment is not applied.

DETAILED DESCRIPTION

Hereinafter, exemplary embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings.

In many cases, an information processing device identifies whether auser who has accessed the information processing device is permitted toaccess the information processing device, and permits the use of theinformation processing device that is an own device only when it isauthenticated that it is a user whose access is permitted. Anauthentication method of a user by a password, a fingerprint, an iris,or the like has been used so far. Recently, there is a demand for anauthentication method having a higher security. Such a method includingperforming an authentication based on a three-dimensional image such asa shape of a face of a user.

Here, an example in which the information processing device is aportable information processing terminal will be described, and theinformation processing device authenticates a user by recognizing ashape of a face that is captured as a three-dimensional image. Theinformation processing device may be applied to an informationprocessing device such as a personal computer (PC) other than a portableinformation processing terminal.

Further, a configuration, a function, a method, and the like describedin the present exemplary embodiment may also be applied to recognize, asan object to be measured, a three-dimensional image other than a shapeof a face. That is, the present invention may be applied to recognize ashape of an object other than a face. Further, a distance to an objectto be measure is not limited.

(Information Processing Device 1)

FIG. 1 is a diagram showing an example of an information processingdevice 1. As described above, the information processing device 1 is,for example, a portable information processing terminal.

The information processing device 1 includes a user interface unit(hereinafter, referred to as a UI unit) 2 and an optical device 3 thatcaptures a three-dimensional image. The UI unit 2 is configured byintegrating, for example, a display device that displays information toa user and an input device to which an instruction for an informationprocessing is input by an operation of the user. The display device is,for example, a liquid crystal display or an organic EL display, and theinput device is, for example, a touch panel.

The optical device 3 includes a light-emitting device 4 and athree-dimensional sensor (hereinafter, referred to as a 3D sensor) 5.The light-emitting device 4 radiates light toward an object to bemeasured, that is, a face in the example described here, in order toacquire a three-dimensional image. The 3D sensor 5 acquires the lightthat is radiated by the light-emitting device 4, is reflected by theface, and is returned. Here, the three-dimensional image of the face isacquired based on a so-called time of flight (TOF) method based onflight time of light. Hereinafter, when a three-dimensional image of aface is acquired, the face is referred to as an object to be measured. Athree-dimensional image of an object to be measure other than a face maybe acquired. The acquisition of a three-dimensional image may bereferred to as 3D sensing. The 3D sensor 5 is an example of the lightreceiving unit.

The information processing device 1 is implemented as a computerincluding a CPU, a ROM, a RAM, and the like. The ROM includes anon-volatile rewritable memory such as a flash memory. Then, programsand constants stored in the ROM are loaded to the RAM and are executedby the CPU, so that the information processing device 1 is operated andvarious information processings are executed.

FIG. 2 is a block diagram showing a configuration of the informationprocessing device 1.

The information processing device 1 includes the optical device 3described above, an optical device control unit 8, and a system controlunit 9. The optical device control unit 8 controls the optical device 3.The optical device control unit 8 includes a shape specifying unit 81.The system control unit 9 controls the entire information processingdevice 1 as a system. The system control unit 9 includes anauthentication processing unit 91. The UI unit 2, a speaker 92, and atwo-dimensional camera (indicated by a 2D camera in FIG. 2 ) 93, and thelike are connected to the system control unit 9.

Hereinafter, the components described above will be described in order.

The light-emitting device 4 provided in the optical device 3 includes awiring substrate 10, a base member 100, a light-emitting element array20, a light diffusing member 30, and a light receiving element formonitoring a light amount (referred to as a PD in FIG. 2 and thefollowing description) 40, a temperature detecting element (referred toas TD in FIG. 2 and the following description) 45, a drive unit 50, aholding unit 60, and a capacitor 70. The light-emitting device 4 furtherincludes passive elements such as a resistor element 6 and a capacitor 7in order to operate the drive unit 50. Although two capacitors 70 areshown, the number of the capacitors 70 may be one or more than two.Further, plural resistor elements 6 and plural capacitors 7 may beprovided. Here, the capacitor 70, the 3D sensor 5, the resistor element6, the capacitor 7, and the like other than the light-emitting elementarray, the PD 40, and the drive unit 50 may be referred to as circuitcomponents without being distinguished from one another.

The light-emitting element array 20, the PD 40, and the TD 45 areprovided on the base member 100. The base member 100 is formed of anelectrically insulating member. Then, the base member 100, the driveunit 50, the capacitor 70, the resistor element 6, and the capacitor 7are provided on the wiring substrate 10.

The light-emitting element array 20 is configured as an array in whichplural light-emitting elements are two-dimensionally arranged (see FIG.3 to be described later). Each of the light-emitting elements is, forexample, a vertical cavity surface emitting laser element (VCSEL). Anexample in which the light-emitting element is a vertical cavity surfaceemitting laser element (VCSEL) will be described in the followingdescription. The vertical cavity surface emitting laser element (VCSEL)is referred to as a VCSEL. The light-emitting element array 20 emitslight in a direction perpendicular to a front surface of the wiringsubstrate 10 or a front surface of the base member 100. Whenthree-dimensional sensing is performed using the ToF method, thelight-emitting element array 20 is driven by the drive unit 50 and isrequired to emit pulsed light (hereinafter, referred to as an emittedlight pulse) having, for example, 100 MHz or more and a rise time of 1ns or less. In the case of face authentication, a distance of lightradiation is about 10 cm to about 1 m. A range in which a 3D shape ismeasured is about 1 m square. Therefore, the light-emitting elementarray 20 is required to have a large output and efficiently dissipateheat generated by the light-emitting element array 20. A distance oflight radiation is referred to as a measurement distance, and a range inwhich a 3D shape of an object to be measured is measured is referred toas a measurement range or a radiation range. A surface virtuallyprovided in the measurement range or the radiation range is referred toas an irradiation surface.

The PD 40 is a photodiode of a pin type or the like that outputs anelectric signal corresponding to an amount of received light(hereinafter, referred to as a received light amount). The PD 40includes a p type Si region serving as an anode, an i (intrinsic) typeSi region, and an n type Si region serving as a cathode. An anodeelectrode is provided in the p type Si region, and a cathode electrodeis provided in the n type Si region. The PD 40 is an example of thelight receiving element, and is an example of the first circuit element.

The TD 45 is a temperature sensor element that measures a temperature ofthe base member 100. The TD 45 is, for example, a negative temperaturecoefficient thermistor (NTC) of a front surface mount type or a positivetemperature coefficient thermistor (PTC). A resistance value of thenegative temperature coefficient thermistor is reduced when atemperature increases, and a resistance value of the positivetemperature coefficient thermistor rapidly increases when a temperatureexceeds a certain constant temperature. The TD 45 uses the abovecharacteristics to detect a temperature of the base member 100 andindirectly monitor a temperature of the light-emitting element array 20.Therefore, the TD 45 may be disposed close to the light-emitting elementarray 20. Although a thermistor does not have polarity, othertemperature sensor elements may have polarity. The TD 45 is a circuitelement other than a light receiving element, and is an example of thesecond circuit element.

The light diffusing member 30 is provided in a manner of covering thelight-emitting element array 20 and the PD 40. That is, the lightdiffusing member 30 is provided to be separated at a predetermineddistance from the light-emitting element array 20 and the PD 40 on thebase member 100 by the holding unit 60 provided on the base member 100.The light diffusing member 30 covers the light-emitting element array 20and the PD 40 refers to that the light diffusing member 30 is providedon an emission path of light emitted from the light-emitting elementarray 20, and the light emitted from the light-emitting element array 20is provided in a manner of passing through the light diffusing member30. As will be described later, the light diffusing member 30 covers thelight-emitting element array 20 and the PD 40 refers to that thelight-emitting element array 20 and the PD 40 overlap the lightdiffusing member 30 in a plan view. Here, the plan view refers to a viewin a case of viewing in an xy plane in FIG. 3 , FIG. 7(a), and the liketo be described later. The PD 40 may be disposed close to thelight-emitting element array 20 at a position covered by the lightdiffusing member 30, so that the PD 40 is likely to receive a part oflight reflected by the light diffusing member 30 among the light emittedfrom the light-emitting element array 20. Here, the light diffusingmember 30 is provided in a manner of covering the TD 45. Alternatively,the light diffusing member 30 may not cover the TD 45. When the lightdiffusing member 30 does not cover the TD 45, an area of the expensivelight diffusing member 30 may be reduced.

The holding unit 60 includes walls 61A, 61B, 62A, and 62B provided in amanner of surrounding the light-emitting element array 20, the PD 40,and the TD 45. Here, it is assumed that an outer shape of the basemember 100, an outer shape of the light diffusing member 30, and anouter shape of the holding unit 60 are the same. Therefore, outer edgesof the base member 100, the light diffusing member 30, and the holdingunit 60 overlap one another. The outer shape of the base member 100 maybe larger than the outer shape of the light diffusing member 30 or theouter shape of the holding unit 60.

Details of the wiring substrate 10, the base member 100, thelight-emitting element array 20, the light diffusing member 30, thedrive unit 50, and the holding unit 60 in the light-emitting device 4will be described later.

The 3D sensor 5 includes plural light receiving cells. For example, eachlight receiving cell is configured to receive pulsed reflected light(hereinafter, referred to as a received light pulse) from an object tobe measured to which an emitted light pulse from the light emittingelement array 20 is emitted, and accumulate electric chargescorresponding to a time until the light receiving cell receives thepulsed reflected light for each light receiving cell. The 3D sensor 5 isimplemented as a device having a CMOS structure in which each lightreceiving cell includes two gates and electric charge accumulating unitscorresponding to the gates. Then, generated photoelectrons aretransferred to any one of the two electric charge accumulating units athigh speed by alternately applying pulses to the two gates. Chargescorresponding to a phase difference between the emitted light pulse andthe received light pulse are accumulated in the two electric chargeaccumulating units. Then, the 3D sensor 5 outputs, as a signal, adigital value corresponding to the phase difference between the emittedlight pulse and the received light pulse for each light receiving cellvia an AD converter. That is, the 3D sensor 5 outputs a signalcorresponding to a time from when light is emitted from thelight-emitting element array 20 to when the light is received by the 3Dsensor 5. The AD converter may be provided in the 3D sensor 5 or may beprovided outside the 3D sensor 5.

As described above, in the case of face authentication, thelight-emitting element array 20 is required to radiate light in aradiation range of about 1 m square at a distance of about 10 cm toabout 1 m. Then, the 3D sensor 5 receives reflected light from theobject to be measured to measure a 3D shape of the object to bemeasured. Therefore, the light-emitting element array 20 is required tohave a large output. Therefore, it is required to efficiently dissipateheat from the light-emitting element array 20.

The shape specifying unit 81 of the optical device control unit 8acquires, from the 3D sensor 5, the digital value obtained for eachlight receiving cell, and calculates a distance to the object to bemeasured for each light receiving cell. Then, a 3D shape of the objectto be measured is specified according to the calculated distance.

The authentication processing unit 91 of the system control unit 9performs an authentication processing related to the use of theinformation processing device 1 when the 3D shape of the object to bemeasured that is a specifying result specified by the shape specifyingunit 81 is a 3D shape stored in advance in the ROM or the like. Theauthentication processing related to the use of the informationprocessing device 1 is, for example, a processing of determining whetherto permit the use of the information processing device 1 that is an owndevice. For example, when it is determined that the 3D shape of the facethat is the object to be measured matches a face shape stored in astorage member such as the ROM, the use of the information processingdevice 1 including various applications provided by the informationprocessing device 1 is permitted.

The shape specifying unit 81 and the authentication processing unit 91are configured by, for example, a program. In addition, the shapespecifying unit 81 and the authentication processing unit 91 may beconfigured by an integrated circuit such as an ASIC or an FPGA. Further,the shape specifying unit 81 and the authentication processing unit 91may be configured by software such as a program and an integratedcircuit such as an ASIC.

In FIG. 2 , the optical device 3, the optical device control unit 8, andthe system control unit 9 are separately shown. Alternatively, thesystem control unit 9 may include the optical device control unit 8. Theoptical device control unit 8 may be included in the optical device 3.Further, the optical device 3, the optical device control unit 8, andthe system control unit 9 may be integrated.

Next, before describing the light-emitting device 4, the light-emittingelement array 20, the light diffusing member 30, and a circuit thatdrives the light-emitting element array 20 that are provided in thelight-emitting device 4 will be described. The circuit that drives thelight-emitting element array 20 includes the drive unit 50, thecapacitor 70, the PD 40, and the TD 45.

(Configuration of Light-Emitting Element Array 20)

FIG. 3 is a plan view showing the light-emitting element array 20. Thelight-emitting element array 20 includes plural VCSELs arranged in atwo-dimensional array. A right direction of the paper is defined as an xdirection, an upper direction of the paper is defined as a y direction.A direction orthogonal to the x direction and the y direction in acounterclockwise manner is defined as a z direction. The x, y, and zdirections are the same in the drawings. A front surface refers to asurface at a +z direction side, and a back surface refers to a surfaceat a −z direction side. The same applies to the other cases.

The VCSEL is a light-emitting element in which an active region servingas a light-emitting region is provided between a lower multilayer filmreflector and an upper multilayer film reflector that are stacked on asemiconductor substrate 200 (see FIG. 4 to be described later), and alaser beam is emitted in a direction perpendicular to the semiconductorsubstrate 200. Therefore, it is easy to form a two-dimensional array.The number of VCSELs provided in the light-emitting element array 20 is,for example, 100 to 1000. The plural VCSELs are connected to one anotherin parallel and are driven in parallel. The number of VCSELs describedabove is an example, and may be set according to a measurement distanceor a measurement range.

An anode electrode 218 (see FIG. 4 to be described later) shared by theplural VCSELs is provided on a front surface of the light-emittingelement array 20. A cathode electrode 214 is provided on a back surfaceof the light-emitting element array 20 (see FIG. 4 to be describedlater). That is, the plural VCSELs are connected in parallel. When theplural VCSELs are connected in parallel and are driven, light having ahigher intensity is emitted at the same time and are radiated onto theobject to be measured as compared with a case where the VCSELs areindividually driven.

Here, it is assumed that a planar shape of the light-emitting elementarray 20 that is a shape in a plan view is a quadrangle. A side surfaceat a +x direction side indicates a side surface 21A, a side surface at a−x direction side indicates a side surface 21B, a side surface at a +ydirection side indicates a side surface 22A, and a side surface at a −ydirection side indicates a side surface 22B. The side surface 21A andthe side surface 21B face each other. Each of the side surface 22A andthe side surface 22B connects the side surface 21A and the side surface21B, and the side surface 22A and the side surface 22B face each other.Here, the side surface 21A is an example of the first side surface, theside surface 21B is an example of the second side surface, the sidesurface 22A is an example of the third side surface, and the sidesurface 22B is an example of the fourth side surface.

(Structure of VCSEL)

FIG. 4 is a diagram showing a cross-sectional structure of one VCSEL inthe light-emitting element array 20. The VCSEL is a VCSEL having a λcavity structure. An upper direction of the paper is defined as a zdirection.

The VCSEL is implemented by sequentially stacking, on the semiconductorsubstrate 200 such as an n type GaAs substrate, an n type lowerdistributed Bragg reflector (DBR) 202 in which AlGaAs layers havingdifferent Al compositions are alternately stacked, an active region 206including a quantum well layer that is interposed between an upperspacer layer and a lower spacer layer, and a p type upper distributedBragg reflector 208 in which AlGaAs layers having different Alcompositions are alternately stacked. Hereinafter, the distributed Braggreflector is referred to as a DBR.

The n type lower DBR 202 is a stacked body in which a Al_(0.9)Ga_(0.1)Aslayer and a GaAs layer are paired, and a thickness of each layer isλ/4n_(r) (in which λ is an oscillation wavelength and n_(r) is arefractive index of a medium), and these layers are alternately stackedin 40 cycles. A carrier concentration after doping with silicon that isan n type impurity is, for example, 3×10¹⁸ cm⁻³.

The active region 206 is formed by stacking a lower spacer layer, aquantum well active layer, and an upper spacer layer. For example, thelower spacer layer is an undoped Al_(0.6)Ga_(0.4)As layer, the quantumwell active layer is an undoped InGaAs quantum well layer and an undopedGaAs barrier layer, and the upper spacer layer is an undopedAl_(0.6)Ga_(0.4)As layer.

The p type upper DBR 208 is a stacked body in which a p typeAl_(0.9)Ga_(0.1)As layer and a GaAs layer are paired, a thickness ofeach layer is λ/4n_(r), and these layers are alternately stacked in 29cycles. A carrier concentration after doping with carbon that is a ptype impurity is, for example, 3×10¹⁸ cm⁻³. A contact layer formed of ptype GaAs may be formed on an uppermost layer of the upper DBR 208, anda current confinement layer 210 formed of p type AlAs may be formed on alowermost layer of the upper DBR 208 or inside the upper DBR 208.

A cylindrical mesa M is formed on the semiconductor substrate 200 byetching stacked semiconductor layers from the upper DBR 208 to the lowerDBR 202. Accordingly, the current confinement layer 210 is exposed at aside surface of the mesa M. An oxidized region 210A oxidized from theside surface of the mesa M and a conductive region 210B surrounded bythe oxidized region 210A are formed in the current confinement layer 210by an oxidation step. In the oxidation step, an AlAs layer has a higheroxidation rate than an AlGaAs layer, and the oxidized region 210A isoxidized from the side surface of the mesa M toward an inner side at asubstantially constant rate, so that a planar shape of the conductiveregion 210B is a shape that reflects an outer shape of the mesa M, thatis, a circular shape, and a center of the conductive region 210Bsubstantially coincides with an axial direction (dashed-dotted line) ofthe mesa M. The mesa M has a columnar structure in the present exemplaryembodiment.

An annular p side electrode 212 that is formed of metal and in whichTi/Au or the like is stacked is formed on an uppermost layer of the mesaM. The p side electrode 212 is in ohmic contact with a contact layer ofthe upper DBR 208. An inner inside of the annular p side electrode 212serves as a light emission port 212A through which a laser beam isemitted to an outer side. That is, in the VCSEL, light is emitted in adirection perpendicular to the semiconductor substrate 200, and theaxial direction of the mesa M serves as an optical axis. Further, thecathode electrode 214 is formed on the back surface of the semiconductorsubstrate 200 as an n side electrode. A front surface of the upper DBR208 inside the p side electrode 212 is a light-emitting surface. Thatis, the optical axial direction of the VCSEL is a light emittingdirection.

An insulating layer 216 is provided in a manner of covering a frontsurface of the mesa M except for a portion of the p side electrode 212to which an anode electrode (the anode electrode 218 to be describedlater) is connected and the light emission port 212A. The anodeelectrode 218 is provided to be in ohmic contact with the p sideelectrode 212 except for the light emission port 212A. The anodeelectrode 218 is shared by the plural VCSELs. That is, the p sideelectrodes 212 in the plural VCSELs provided in the light-emittingelement array 20 are connected in parallel by the anode electrode 218.The anode electrode 218 is an example the an upper surface electrode ofthe light-emitting element array.

The VCSEL may oscillate in a single transverse mode or in a multipletransverse mode. For example, an optical output of one VCSEL is 4 mW to8 mW. Therefore, for example, when the light-emitting element array 20includes 500 VCSELs, an optical output of the light-emitting elementarray 20 is 2 W to 4 W. In such a light-emitting element array 20 havinga large output, heat generated from the light-emitting element array 20is large.

(Configuration of Light Diffusing Member 30)

FIGS. 5(a) and 5(b) are diagrams showing an example of the lightdiffusing member 30. FIG. 5(a) is a plan view and FIG. 5(b) is across-sectional view taken along a line VB-VB in FIG. 5(a). In FIG.5(a), a right direction of the paper is defined as the x direction, andan upper direction of the paper is defined as the y direction. Adirection orthogonal to the x direction and the y direction in acounterclockwise manner is defined as the z direction. In FIG. 5(b), aright direction of the paper is defined as the x direction, and an upperdirection of the paper is defined as the z direction.

As shown in FIG. 5(b), the light diffusing member 30 includes a resinlayer 32 formed with unevenness for diffusing light onto a back surfaceof a flat glass base member 31 of which two surfaces are parallel toeach other. The light diffusing member 30 further expands a spread angleof light incident from the VCSEL of the light-emitting element array 20and emits the light. That is, the unevenness formed in the resin layer32 of the light diffusing member 30 refracts or scatters light toincrease a spread angle α of incident light to a larger spread angle βof emitted light. That is, as shown in FIGS. 5(a) and 5(b) the spreadangle β of light that is transmitted through the light diffusing member30 and is emitted from the light diffusing member 30 is larger than thespread angle α of the light emitted from the VCSEL (α<β). Therefore, anarea of an irradiation surface irradiated with the light emitted fromthe light-emitting element array 20 in a case where the light diffusingmember 30 is used is larger than a case where the light diffusing member30 is not used. In addition, a light density on the irradiation surfaceis reduced. The light density refers to radiance per unit area, and thespread angles α and β are full widths at half maximum (FWHM).

A planar shape of the light diffusing member 30 is, for example, aquadrangle. A width W_(x) of the light diffusing member 30 in the xdirection and a vertical width W_(y) of the light diffusing member 30 inthe y direction is 1 mm to 10 mm, and a thickness t_(d) of the lightdiffusing member 30 in the z direction is 0.1 mm to 1 mm. When the lightdiffusing member 30 has a size and a shape as described above, a lightdiffusing member suitable for face authentication of a portableinformation processing terminal or measurement at a relatively shortdistance of about several meters is provided. The planar shape of thelight diffusing member 30 may be other shapes such as a polygon or acircle.

(Circuit that Drives Light Emitting Element Array 20)

When the light-emitting element array 20 is driven at a higher speed,low-side driving may be performed. The low-side driving refers to aconfiguration in which a drive element such as a MOS transistor ispositioned at a downstream side of a current path relative to a drivetarget such as a VCSEL. Conversely, a configuration in which a driveelement is positioned at an upstream side is referred to as high-sidedriving.

FIG. 6 is a diagram showing an example of an equivalent circuit thatdrives the light-emitting element array 20 by low-side driving. FIG. 6shows a VCSEL of the light-emitting element array 20, the drive unit 50,the capacitor 70, a power source 82, the PD 40, a light amount detectionresistor element 41 that detects a current flowing through the PD 40,the TD 45, and a temperature detection resistor element 46 that detectsa current flowing through the TD 45. The capacitor 70 is connected inparallel to the power source 82.

The power source 82 is provided in the optical device control unit 8shown in FIG. 2 . The power source 82 generates a direct current voltagehaving a positive side as a power source potential and a negative sideas a ground potential. The power source potential is supplied to a powersource line 83, and the ground potential is supplied to a ground line84.

As described above, the light-emitting element array 20 is configured byconnecting plural VCSELs in parallel. The anode electrode 218 (see FIG.4 ) of the VCSEL is connected to the power source line 83.

The drive unit 50 includes an n channel MOS transistor 51 and a signalgeneration circuit 52 that turns on and turns off the MOS transistor 51.A drain of the MOS transistor 51 is connected to the cathode electrode214 (see FIG. 4 ) of the VCSEL. A source of the MOS transistor 51 isconnected to the ground line 84. A gate of the MOS transistor 51 isconnected to the signal generation circuit 52. That is, the VCSEL andthe MOS transistor 51 of the drive unit 50 are connected in seriesbetween the power source line 83 and the ground line 84. The signalgeneration circuit 52 generates an “H level” signal for turning on theMOS transistor 51 and an “L level” signal for turning off the MOStransistor 51 under the control of the optical device control unit 8.

The capacitor 70 has one terminal connected to the power source line 83and the other terminal connected to the ground line 84. That is, thecapacitor 70 is connected in parallel to the power source 82. When thereare plural capacitors 70, the plural capacitors 70 are connected inparallel. The capacitor 70 is an electrolytic capacitor, a ceramiccapacitor, and the like.

A cathode electrode of the PD 40 is connected to the power source line83, and an anode electrode of the PD 40 is connected to one terminal ofthe light amount detection resistor element 41. The other terminal ofthe light amount detection resistor element 41 is connected to theground line 84. That is, the PD 40 and the light amount detectionresistor element 41 are connected in series between the power sourceline 83 and the ground line 84. An output terminal 42 that is aconnection point between the PD 40 and the light amount detectionresistor element 41 is connected to the optical device control unit 8.

One terminal of the temperature detection resistor element 46 isconnected to the power source line 83, and the other terminal of thetemperature detection resistor element 46 is connected to one electrodeof the TD 45. The other electrode of the TD 45 is connected to theground line 84. That is, the temperature detection resistor element 46and the TD 45 are connected in series between the power source line 83and the ground line 84. An output terminal 47 that is a connection pointbetween the temperature detection resistor element 46 and the TD 45 isconnected to the optical device control unit 8.

Next, a method of driving the light-emitting element array 20 that islow-side driving will be described.

First, it is assumed that a signal generated by the signal generationcircuit 52 in the drive unit 50 is at an “L level”. In this case, theMOS transistor 51 is turned off. That is, no current flows between thesource and the drain of the MOS transistor 51. Therefore, no currentflows through the VCSEL connected in series with MOS transistor 51. TheVCSEL does not emit light.

At this time, the capacitor 70 is charged by the power source 82. Thatis, one terminal of the capacitor 70 connected to the power source line83 is a power source potential, and the other terminal of the capacitor70 connected to the ground line 84 is a ground potential. The capacitor70 accumulates electric charges determined by a capacitance, a powersource voltage (=power source potential−ground potential), and time.

Next, when a signal generated by the signal generation circuit 52 in thedrive unit 50 is at an “H level”, the MOS transistor 51 shifts from anOFF state to an ON state. Then, the electric charges accumulated in thecapacitor 70 are discharged, and a current flows through the MOStransistor 51 and the VCSEL that are connected in series, so that theVCSEL emits light.

When a signal generated by the signal generation circuit 52 in the driveunit 50 is at an “L level”, the MOS transistor 51 shifts from an ONstate to an OFF state. Accordingly, the VCSEL stops emitting light.Then, the power source 82 resumes the accumulation of electric chargesin the capacitor 70.

As described above, each time when the signal output from the signalgeneration circuit 52 shifts between the “L level” and the “H level”,the MOS transistor 51 is repeatedly turned on and turned off, andemission and non-emission that is a state in which the VCSEL stopsemitting light are repeated. That is, a light pulse is emitted from theVCSEL. Repetition of ON and OFF of the MOS transistor 51 may be referredto as switching. As shown in FIG. 6 , the equivalent circuit includesthe light-emitting element array 20, the MOS transistor 51, thecapacitor 70, and the like, and a current path to the light-emittingelement array 20 is referred to as a circuit or a circuit that drivesthe light-emitting element array 20.

Electric charges (a current) may be directly supplied from the powersource 82 to the VCSEL without providing the capacitor 70.Alternatively, these electric charges are accumulated in the capacitor70, and the accumulated charges are discharged when the MOS transistor51 is switched from an OFF state to an ON state to rapidly supply acurrent to the VCSEL, so that a rise time of light emission of the VCSELis reduced.

The PD 40 is connected in a reverse direction between the power sourceline 83 and the ground line 84 via the light amount detection resistorelement 41. Therefore, no current flows in a state in which light is notradiated. As described above, when the PD 40 receives a part of lightreflected by the light diffusing member 30 among the light emitted fromthe VCSEL, a current corresponding to a received light amount flowsthrough the PD 40. Therefore, the current flowing through the PD 40 ismeasured as a voltage of the output terminal 42, and a light intensityof the light-emitting element array 20 is detected. Therefore, theoptical device control unit 8 controls the light intensity of thelight-emitting element array 20 to be a predetermined light intensityaccording to the received light amount of the PD 40. For example, whenthe light intensity of the light-emitting element array 20 is lower thanthe predetermined light intensity, the optical device control unit 8increases the power source potential of the power source 82 to increasean amount of electric charges accumulated in the capacitor 70, therebyincreasing a current flowing through the VCSEL. On the other hand, whenthe light intensity of the light-emitting element array 20 is higherthan the predetermined light intensity, the power source potential ofthe power source 82 is lowered to reduce an amount of electric chargesaccumulated in the capacitor 70, thereby reducing a current flowingthrough the VCSEL. In this manner, the light intensity of thelight-emitting element array 20 is controlled.

When the received light amount of the PD 40 is extremely low, the lightdiffusing member 30 may be removed or damaged, and the light emittedfrom the light-emitting element array 20 may be directly radiated to theoutside. In such a case, the light intensity of the light-emittingelement array 20 is reduced by the optical device control unit 8. Forexample, emission of light from the light-emitting element array 20,that is, radiation of light onto an object to be measured, is stopped.

As described above, the PD 40 is provided to detect the light intensityof the light-emitting element array 20. Therefore, when the PD 40 isdisposed far from the light-emitting element array 20, a received lightamount is reduced, and detection sensitivity of the light intensity ofthe light-emitting element array 20 is reduced. Therefore, the PD 40 maybe disposed in the vicinity of the light-emitting element array 20.

The TD 45 is connected in series with the temperature detection resistorelement 46 between the power source line 83 and the ground line 84.Therefore, the output terminal 47 has a voltage obtained by dividing thepower source voltage (=power source potential−ground potential) by thetemperature detection resistor element 46 and the TD 45. When the TD 45is, for example, a negative temperature coefficient (NTC) thermistor, aresistance value of the TD 45 is reduced along with an increase in thetemperature of the base member 100 as described above. In this case, avoltage of the output terminal 47 is reduced along with an increase inthe temperature of the base member 100. The optical device control unit8 detects the temperature of the base member 100, that is, a temperatureof the light-emitting element array 20, based on the voltage of theoutput terminal 47. When the temperature of the light-emitting elementarray 20 exceeds a predetermined allowable temperature, an operation ofthe light-emitting element array 20 may be unstable or broken.Therefore, when the optical device control unit 8 detects that thetemperature of the light-emitting element array 20 exceeds the allowabletemperature based on the voltage of the output terminal 47, the opticaldevice control unit 8 controls the drive unit 50 to reduce a currentflowing through the light-emitting element array 20 or cut off thecurrent flowing through the light-emitting element array 20. In thismanner, overheating of the light-emitting element array 20 is prevented.

As described above, the TD 45 is provided to detect the temperature ofthe light-emitting element array 20. Therefore, when the TD 45 isdisposed far from the light-emitting element array 20, a change in thetemperature of the TD 45 is reduced, and detection sensitivity of thetemperature of the light-emitting element array 20 is reduced.Therefore, the TD 45 may be disposed in the vicinity of thelight-emitting element array 20.

That is, the PD 40 and the TD 45 are examples of circuit elementsdisposed close to the light-emitting element array 20.

(Light-Emitting Device 4)

Next, the light-emitting device 4 will be described in detail.

FIGS. 7(a) to 7(c) are diagrams showing the light-emitting device 4 towhich the present exemplary embodiment is applied. FIG. 7(a) is a planview, FIG. 7(b) is a cross-sectional view taken along a line VIIB-VIIBin FIG. 7(a), and FIG. 7(c) are cross-sectional views taken along a lineVIIC-VIIC in FIG. 7(a). In FIG. 7(a), a right direction of the paper isdefined as the x direction, and an upper direction of the paper isdefined as the y direction. A direction orthogonal to the x directionand the y direction in a counterclockwise manner is defined as the zdirection. In FIGS. 7(b) and 7(c), a right direction of the paper isdefined as the x direction, and an upper direction of the paper isdefined as the z direction. The same applies to the same drawings to bedescribed below.

As shown in FIGS. 7(b) and 7(c), the base member 100 and the drive unit50 are provided on the wiring substrate 10 in the light-emitting device4. The light-emitting element array 20, the PD 40, the TD 45, and theholding unit 60 are provided on the base member 100. The light diffusingmember 30 is provided on the holding unit 60. As shown in FIGS. 7(a) and7(c), the light-emitting element array 20, the PD 40, and the TD 45 arecovered by the light diffusing member 30. Therefore, the PD 40 receivesa part of light reflected by the back surface of the light diffusingmember 30 among the light emitted from the light-emitting element array20. The holding unit 60 may be provided on the wiring substrate 10.

As shown in FIG. 7(a), the PD 40, the light-emitting element array 20,the TD 45, and the drive unit 50 are linearly arranged in the xdirection in the light-emitting device 4. Here, it is assumed that anarea occupied by the PD 40 on the base member 100 is larger than an areaoccupied by the TD 45 on the base member 100. An area occupied on thebase member 100 is referred to as an occupation area in the followingdescription. That is, in the light-emitting device 4, the PD 40 and theTD 45 are disposed close to the light-emitting element array 20, and theTD 45 having a small occupation area is disposed at a side of thelight-emitting element array 20 close to the drive unit 50, and the PD40 having a large occupation area is disposed at a side of thelight-emitting element array 20 far from the drive unit 50.

With such an arrangement, a distance D1 from an end portion of thelight-emitting element array 20 at the drive unit 50 side to the driveunit 50 shown in FIG. 7(a) is shorter than a distance D2 in acomparative example to be described later. As will be described later, alight-emitting element array cathode wiring pattern 12 that connects thecathode electrode 214 of the light-emitting element array 20 and thedrain (see FIG. 6 ) of the MOS transistor 51 of the drive unit 50 isprovided linearly in the x direction. Therefore, when the distance D1from the end portion of the light-emitting element array 20 at the driveunit 50 side to the drive unit 50 is short, the light-emitting elementarray cathode wiring pattern 12 is short, and inductance of the circuitthat drives the light-emitting element array 20 is small.

This will be described in detail below.

The wiring substrate 10 is, for example, a three-layer multilayersubstrate. That is, the wiring substrate 10 includes a first conductivelayer, a second conductive layer, and a third conductive layer from aside where the base member, the drive unit 50, and the like are mounted.Further, an insulating layer is provided between the first conductivelayer and the second conductive layer, and between the second conductivelayer and the third conductive layer. For example, the third conductivelayer is the power source line 83, and the second conductive layer isthe ground line 84. Then, light-emitting element array anode wiringpatterns 11-1 and 11-2 and the light-emitting element array cathodewiring pattern 12 that constitute a part of a current path to thelight-emitting element array 20, a PD anode wiring pattern 13 and a PDcathode wiring pattern 14 that constitute a current path to the PD 40,and a TD anode wiring pattern 15 TD and a TD cathode wiring pattern 16(see FIGS. 8(a) to 8(c) to be described later) that constitute a part ofa current path to the TD 45 are formed by the first conductive layer.Further, wiring patterns to which circuit components such as thecapacitor 70, the resistor element 6, and the capacitor 7 are connectedare formed by the first conductive layer, and these wiring patterns arenot shown. In this manner, the wiring substrate 10 is a multilayersubstrate, the power source line 83 is the third conductive layer, andthe ground line 84 is the second conductive layer, so that a fluctuationin the power source potential and the ground potential is prevented. Apath through which a current flows, such as the light-emitting elementarray anode wiring pattern 11-1 and 11-2, the light-emitting elementarray cathode wiring pattern 12, the PD anode wiring pattern 13, the PDcathode wiring pattern 14, the TD anode wiring pattern 15, and the TDcathode wiring pattern 16, is referred to as a wiring pattern. Thewiring pattern formed of the first conductive layer is electricallyconnected to the second conductive layer or the third conductive layervia a via. For example, the via is a conductive portion formed byembedding a conductive material in a hole provided in a manner ofpassing through the wiring substrate 10 in a thickness direction.

The first conductive layer, the second conductive layer, and the thirdconductive layer are formed of a metal such as copper (Cu) or silver(Ag) or a conductive material such as a conductive paste containingthese metals. The insulating layer is formed of epoxy resin, ceramics,or the like.

The base member 100 is formed of an electrically insulating material.Since the light-emitting element array 20 is provided on the base member100, the base member 100 may be formed of a heat dissipation member thathas an electrically insulating property and has a higher thermalconductivity than the wiring substrate 10. Examples of the heatdissipation member that has an electrically insulating property includeceramics such as silicon nitride and aluminum nitride. When the basemember 100 is a heat dissipation member, heat generated by thelight-emitting element array 20 is easily transferred to the holdingunit 60 and the light diffusing member 30 via the base member 100 and isdissipated, and heat dissipation efficiency is improved.

Light-emitting element array anode wiring patterns 111-1F and 111-2F anda light-emitting element array cathode wiring pattern 112F thatconstitute a part of a current path to the light-emitting element array20, a PD anode wiring pattern 113F and a PD cathode wiring pattern 114Fthat constitute a part of a current path to the PD 40, a TD anode wiringpattern 115F and a TD cathode wiring pattern 116F that constitute a partof a current path to the TD 45 are provided on a front surface of thebase member 100. Light-emitting element array anode wiring patterns111-1B (see FIG. 8(c) to be described later) and 111-2B and alight-emitting element array cathode wiring pattern 112B that constitutea part of a current path to the light-emitting element array 20, a PDanode wiring pattern 113B (see FIG. 8(b) to be described later) and a PDcathode wiring pattern 114B that constitute a part of a current path tothe PD 40, a TD anode wiring pattern 115B (see FIG. 8(c) to be describedlater) and a TD cathode wiring pattern 116B that constitute a part of acurrent path to the TD 45 are provided on a back surface of the basemember 100. The wiring patterns of the same number are connected to eachother via a via on the front surface and the back surface of the basemember 100. For example, as shown in FIG. 7(b), the light-emittingelement array anode wiring pattern 111-2F provided on the front surfaceand the light-emitting element array cathode wiring pattern 111-2Bprovided on the back surface are connected via a via 111-2V. The via isdenoted by adding “V” to the reference number of the wiring pattern.Here, the via is, for example, a conductive portion formed by embeddinga conductive material in a hole that is provided in a manner of passingthrough the base member 100, and the via electrically connects thewiring pattern on the front surface and the wiring pattern on the backsurface. The inductance of the circuit is reduced by connecting thewiring patterns using plural vias.

Then, the light-emitting element array cathode wiring pattern 112F ofthe base member 100 and the cathode electrode 214 (see FIG. 4 ) of thelight-emitting element array 20 are connected by a conductive adhesiveor the like. The light-emitting element array anode wiring pattern111-1F of the base member 100 and the anode electrode 218 (see FIG. 4 )of the light-emitting element array 20 are connected by a bonding wire23A at the side surface 22A side of the light-emitting element array 20,and the light-emitting element array anode wiring pattern 111-2F of thebase member 100 and the anode electrode 218 (see FIG. 4 ) of thelight-emitting element array 20 are connected by a bonding wire 23B atthe side surface 22B side of the light-emitting element array 20. Here,the light-emitting element array anode wiring pattern 111-1F is providedat the side surface 22A side of the light-emitting element array 20, andthe light-emitting element array anode wiring pattern 111-2F is providedat the side surface 22B side of the light-emitting element array 20. Thelight-emitting element array anode wiring patterns may not be providedat the side surface 21A side and the side surface 21B side of thelight-emitting element array 20. In this manner, the bonding wires thatconnect the anode electrode 218 and the light-emitting element arrayanode wiring patterns are not provided at the side surface 21A side andthe side surface 21B side of the light-emitting element array 20.Therefore, the PD 40 and the TD 45 that are examples of circuit elementsdesired to be disposed close to the light-emitting element array 20 arearranged close to the light-emitting element array 20. Here, the bondingwires (the bonding wires 23A and 23B) are examples of a wiring memberextending from an upper surface electrode of the light-emitting elementarray 20 toward an outer side of the light-emitting element array 20.

The light-emitting element array anode wiring pattern 111-1F provided onthe front surface of the base member 100 is connected to thelight-emitting element array anode wiring pattern 11-1 provided on thewiring substrate 10 via the light-emitting element array anode wiringpattern 111-1B provided on the back surface. Similarly, thelight-emitting element array anode wiring pattern 111-2F provided on thefront surface of the base member 100 is connected to the light-emittingelement array anode wiring pattern 11-2 provided on the wiring substrate10 via the light-emitting element array anode wiring pattern 111-2Bprovided on the back surface. The light-emitting element array anodewiring patterns 11-1 and 11-2 are connected to one terminal of thecapacitor 70. The capacitor 70 may be provided for each of thelight-emitting element array anode wiring patterns 11-1 and 11-2.

In the PD 40, the cathode electrode of the PD 40 is bonded to the PDcathode wiring pattern 114F of the base member 100 by a conductiveadhesive, and the anode electrode of the PD 40 is connected to the PDanode wiring pattern 113F of the base member 100 by a bonding wire 23C.

In the TD 45, one terminal (in a case where the TD 45 has polarity, aterminal at a positive side) is connected to the TD anode wiring pattern115F of the base member 100, and the other terminal (in a case where theTD 45 has polarity, the terminal at a negative side) is connected to theTD cathode wiring pattern 116F of the base member 100 by a conductiveadhesive or solder.

The light-emitting element array anode wiring patterns 11-1 and 11-2 andthe light-emitting element array cathode wiring pattern 12 provided onthe wiring substrate 10 are respectively connected to the light-emittingelement array anode wiring patterns 111-1B and 111-2B and thelight-emitting element array cathode wiring pattern 112B provided on theback surface of the base member 100. Similarly, the PD anode wiringpattern 13 and the PD cathode wiring pattern 14 provided on the wiringsubstrate 10 are respectively connected to the PD anode wiring pattern113B and the PD cathode wiring pattern 114B provided on the back surfaceof the base member 100. The TD anode wiring pattern 15 (see FIG. 8(a) tobe described later) and the TD cathode wiring pattern 16 provided on thewiring substrate 10 are respectively connected to the TD anode wiringpattern 115B (see FIG. 8(c) to be described later) and the TD cathodewiring pattern 116B provided on the back surface of the base member 100.The wiring patterns of the wiring substrate 10 and the wiring patternsof the base member 100 are connected by a conductive adhesive or thelike.

As shown in FIG. 7(b), in a cross-sectional view taken along the lineVIIB-VIIB shifted to a −y direction side from a center in the ydirection, the light-emitting element array anode wiring pattern 11-2 ofthe wiring substrate 10 and the light-emitting element array anodewiring pattern 111-2B provided on the back surface of the base member100 are connected to each other. The light-emitting element array anodewiring pattern 111-2B of the base member 100 is connected to thelight-emitting element array anode wiring pattern 111-2F provided on thefront surface of the base member 100 via the via 111-2V. Thelight-emitting element array anode wiring pattern 111-2F of the basemember 100 is connected to the anode electrode 218 (see FIG. 4 ) of thelight-emitting element array 20 via the bonding wire 23B.

Similarly, the PD cathode wiring pattern 14 of the wiring substrate 10is connected to the PD cathode wiring pattern 114B provided on the backsurface of the base member 100. The PD cathode wiring pattern 114B ofthe base member 100 is connected to the PD cathode wiring pattern 114Fprovided on the front surface of the base member 100 via a via 114V. ThePD cathode wiring pattern 114F of the base member 100 is connected tothe cathode of the PD 40.

Further, the TD cathode wiring pattern 16 of the wiring substrate 10 isconnected to the TD cathode wiring pattern 116B provided on the backsurface of the base member 100. The TD cathode wiring pattern 116B ofthe base member 100 is connected to the TD cathode wiring pattern 116Fprovided on the front surface of the base member 100 via a via 116V. TheTD cathode wiring pattern 116F of the base member 100 is connected tothe cathode of the TD 45.

That is, in the cross section taken along the line VIIB-VIIB, thelight-emitting element array anode wiring pattern 11-2 of the wiringsubstrate 10, the light-emitting element array anode wiring pattern111-2B provided on the back surface of the base member 100, and thelight-emitting element array anode wiring pattern 111-2F provided on thefront surface of the base member 100 are provided in a manner of facingone another. Similarly, the PD cathode wiring pattern 14 of the wiringsubstrate 10, the PD cathode wiring pattern 114B provided on the backsurface of the base member 100, and the PD cathode wiring pattern 114Fprovided on the front surface of the base member 100 are provided in amanner of facing one another. Further, the TD cathode wiring pattern 16of the wiring substrate 10, the TD cathode wiring pattern 116B providedon the back surface of the base member 100, and the TD cathode wiringpattern 116F provided on the front surface of the base member 100 areprovided in a manner of facing one another. Although not shown, thelight-emitting element array anode wiring pattern 11-1 of the wiringsubstrate 10, the light-emitting element array anode wiring pattern111-1B provided on the back surface of the base member 100, and thelight-emitting element array anode wiring pattern 111-1F provided on thefront surface of the base member 100 are provided in a manner of facingone another.

On the other hand, as shown in FIG. 7(c), in the cross-sectional viewtaken along the line VIIC-VIIC in the center in the y direction, thelight-emitting element array cathode wiring pattern 12 of the wiringsubstrate 10 is provided in a manner of extending from a lower side ofthe light-emitting element array 20 to the drive unit 50. Thelight-emitting element array cathode wiring pattern 12 is connected tothe light-emitting element array cathode wiring pattern 112B provided onthe back surface of the base member 100. The light-emitting elementarray cathode wiring pattern 112B is connected to the light-emittingelement array cathode wiring pattern 112F provided on the front surfaceof the base member 100 via a via 112V. The light-emitting element arraycathode wiring pattern 112F is connected to the cathode electrode 214 ofthe light-emitting element array 20.

The PD cathode wiring pattern 14 of the wiring substrate 10 and the PDcathode wiring pattern 114B provided on the back surface of the basemember 100 are connected to each other. The PD cathode wiring pattern114B is connected to the PD cathode wiring pattern 114F provided on thefront surface of the base member 100 via the via 114V. The PD cathodewiring pattern 114F is connected to the cathode electrode of the PD 40.In the cross-sectional view taken along the line VIIC-VIIC, the PDcathode wiring pattern 14 provided on the wiring substrate 10 and the PDcathode wiring pattern 114B provided on the back surface of the basemember 100 may not be provided.

In the cross section taken along the line VIIC-VIIC shown in FIG. 7(c),neither the TD anode wiring pattern 115F nor the TD cathode wiringpattern 116F on the base member 100 is connected to the light-emittingelement array cathode wiring pattern 12 provided on the wiring substrate10.

That is, in the cross section taken along the line VIIC-VIIC, thelight-emitting element array cathode wiring pattern 112B provided on theback surface of the base member 100 and the light-emitting element arraycathode wiring pattern 112F provided on the front surface of the basemember 100 are provided in a manner of facing each other, and thelight-emitting element array cathode wiring pattern 12 of the wiringsubstrate 10 is provided in a manner of extending from a portion facingthe light-emitting element array cathode wiring pattern 112B to thedrive unit 50. Alternatively, a wiring pattern facing the TD anodewiring pattern 115F or the TD cathode wiring pattern 116F is notprovided on the back surface of the base member 100. That is, the TDanode wiring pattern 115F or the TD cathode wiring pattern 116F providedon the base member 100 and the light-emitting element array cathodewiring pattern 12 provided on the wiring substrate 10three-dimensionally intersect with one another but are not electricallyconnected to each other. That is, the base member 100 is provided acrossthe light-emitting element array cathode wiring pattern 12. In thismanner, the light-emitting element array cathode wiring pattern 12 ofthe wiring substrate 10 is provided in a manner of extending from thelight-emitting element array 20 to the drive unit 50 on the back surfaceof the base member 100, and the TD 45 is provided in a region on thebase member 100 that is a region overlapping the light-emitting elementarray cathode wiring pattern 12 in a plan view. When the base member 100is not provided across the light-emitting element array cathode wiringpattern 12 and the base member 100 is provided at one side in a widthdirection of the light-emitting element array cathode wiring pattern 12,a size of the light-emitting device 4 is increased.

As described above, as shown in FIG. 7(a), in the light-emitting device4 to which the first exemplary embodiment is applied, the PD 40 and theTD 45 are disposed close to the light-emitting element array 20, and theTD 45 having a smaller occupation area than the PD 40 is disposedbetween the light-emitting element array 20 and the drive unit 50, sothat the distance D1 between the light-emitting element array 20 and thedrive unit 50 is reduced, and a wiring pattern (here, the light-emittingelement array cathode wiring pattern 12) that connects thelight-emitting element array 20 and the drive unit 50 is linearlyprovided. Accordingly, the wiring pattern (here, the light-emittingelement array cathode wiring pattern 12) that connects thelight-emitting element array 20 and the drive unit 50 is shortened, andan increase in inductance of the circuit is prevented.

Next, the wiring patterns provided on the wiring substrate 10 and thebase member 100 will be described in detail.

FIGS. 8(a) to 8(c) are diagrams showing wiring patterns provided on thewiring substrate 10 and the base member 100. FIG. 8(a) shows a frontsurface of the wiring substrate 10, FIG. 8(b) shows the front surface ofthe base member 100, and FIG. 8(c) shows the back surface of the basemember 100. FIG. 8(a) shows a wiring pattern formed by the firstconductive layer of the wiring substrate 10, and does not show wiringpatterns formed by the second conductive layer that is the ground line84 and the third conductive layer that is the power source line 83. Thesecond conductive layer and the third conductive layer are solid filmsexcept for a portion where a via used to connect to the wiring patternformed by the first conductive layer is provided.

The light-emitting element array anode wiring patterns 11-1 and 11-2 andthe light-emitting element array cathode wiring pattern 12 are providedon the front surface of the wiring substrate 10 shown in FIG. 8(a). Thelight-emitting element array cathode wiring pattern 12 has aquadrangular planar shape. The light-emitting element array anode wiringpatterns 11-1 and 11-2 are provided adjacent to the light-emittingelement array cathode wiring pattern 12 in the ±y direction. Further,the PD anode wiring pattern 13, the PD cathode wiring pattern 14, the TDanode wiring pattern 15, and the TD cathode wiring pattern 16 areprovided on the front surface of the wiring substrate 10. The PD anodewiring pattern 13 and the PD cathode wiring pattern 14 are provided atthe −x direction side of the light-emitting element array cathode wiringpattern 12, and the TD anode wiring pattern 15 and the TD cathode wiringpattern 16 are provided in a manner of sandwiching the light-emittingelement array cathode wiring pattern 12 in the ±y direction.

The light-emitting element array anode wiring patterns 111-1F and 111-2Fand the light-emitting element array cathode wiring pattern 112F areprovided on the front surface of the base member 100 shown in FIG. 8(b).The light-emitting element array cathode wiring pattern 112F has aquadrangular planar shape corresponding to the planar shape of thelight-emitting element array 20 shown in FIG. 3 . The light-emittingelement array anode wiring patterns 111-1F and 111-2F are providedadjacent to the light-emitting element array cathode wiring pattern 112Fin the ±y direction. Further, the PD anode wiring pattern 113F, the PDcathode wiring pattern 114F, the TD anode wiring pattern 115F, and theTD cathode wiring pattern 116F are provided on the front surface of thebase member 100.

The light-emitting element array anode wiring pattern 111-1B connectedto the light-emitting element array anode wiring pattern 111-1F via avia 111-1V, the light-emitting element array anode wiring pattern 111-2Bconnected to the light-emitting element array anode wiring pattern111-2F via a via 111-2V, the light-emitting element array cathode wiringpattern 112B connected to the light-emitting element array cathodewiring pattern 112F via the via 112V, the PD anode wiring pattern 113Bconnected to the PD anode wiring pattern 113F via a via 113V, the PDcathode wiring pattern 114B connected to the PD cathode wiring pattern114F via the via 114V, the TD anode wiring pattern 115B connected to theTD anode wiring pattern 115F via a via 115V, and the TD cathode wiringpattern 116B connected to the TD cathode wiring pattern 116F via the via116V are provided on the back surface of the base member 100 shown inFIG. 8(c). The wiring patterns on the front surface of the base member100 shown in FIG. 8(b) and the wiring patterns on the back surface ofthe base member 100 shown in FIG. 8(c) are mirror-inverted except forthe TD anode wiring pattern 115F, the TD cathode wiring pattern 116F,the TD anode wiring pattern 115B, and the TD cathode wiring pattern116B. That is, the wiring patterns on the front surface and the wiringpatterns on the back surface of the base member 100 are provided in amanner of overlapping one another in a plan view. The light-emittingelement array cathode wiring pattern 12 is a wiring pattern on thewiring substrate 10 that is connected to the light-emitting elementarray 20 and extends from the back surface side of the base member 100toward the drive unit 50.

On the other hand, the TD anode wiring pattern 115F and the TD cathodewiring pattern 116F, the TD anode wiring pattern 115B and the TD cathodewiring pattern 116B are provided such that the TD anode wiring pattern115F and the TD cathode wiring pattern 116F on the front surface arelonger in the y direction than the TD anode wiring pattern 115B and theTD cathode wiring pattern 116B on the back surface and extend to thevicinity of a center portion in the y direction of the base member 100.Two terminals of the TD 45 are respectively connected to the TD anodewiring pattern 115F and the TD cathode wiring pattern 116F in thevicinity of the center portion in the y direction of the base member100.

Then, when the base member 100 is disposed at a position surrounded by abroken line on the wiring substrate 10 shown in FIG. 8(a), thelight-emitting element array anode wiring patterns 11-1 and 11-2 of thewiring substrate 10 are connected to the light-emitting element arrayanode wiring patterns 111-1B and 111-2B of the base member 100, and thelight-emitting element array cathode wiring pattern 12 of the wiringsubstrate 10 is connected to the light-emitting element array cathodewiring pattern 112B of the base member 100. Similarly, the PD anodewiring pattern 13 of the wiring substrate 10 is connected to the PDanode wiring pattern 113B of the base member 100, and the PD cathodewiring pattern 14 of the wiring substrate 10 is connected to the PDcathode wiring pattern 114B of the base member 100. Further, the TDanode wiring pattern 15 of the wiring substrate 10 is connected to theTD anode wiring pattern 115B of the base member 100, and the TD cathodewiring pattern 16 of the wiring substrate 10 is connected to the TDcathode wiring pattern 116B of the base member 100.

At this time, when the TD anode wiring pattern 115B and the TD cathodewiring pattern 116B provided on the back surface of the base member 100have the same shape as the TD anode wiring pattern 115F and the TDcathode wiring pattern 116F provided on the front surface of the basemember 100, the TD anode wiring pattern 115B and the TD cathode wiringpattern 116B short-circuit the light-emitting element array cathodewiring pattern 12 of the wiring substrate 10, the TD anode wiringpattern 115B, and the TD cathode wiring pattern 116B. Therefore, the TDanode wiring pattern 115B and the TD cathode wiring pattern 116Bprovided on the back surface of the base member 100 have shorter lengthstoward the center portion in the y direction than the TD anode wiringpattern 115F and the TD cathode wiring pattern 116F provided on thefront surface of the base member 100, and do not short-circuit thelight-emitting element array cathode wiring pattern 12 of the wiringsubstrate 10, the TD anode wiring pattern 115B, and the TD cathodewiring pattern 116B. That is, in order to dispose the TD 45 between thelight-emitting element array 20 and the drive unit 50, the TD anodewiring pattern 115F and the TD cathode wiring pattern 116F are providedon the base member 100 and three-dimensionally intersect with thelight-emitting element array cathode wiring pattern 12 provided on thewiring substrate 10 so as not to short-circuit the light-emittingelement array cathode wiring pattern 12.

The light-emitting element array 20, the PD 40, and the TD 45 aremounted on the base member 100 before the base member 100 is disposed onthe wiring substrate 10. That is, the cathode electrode 214 (see FIG. 4) of the light-emitting element array 20 is bonded onto thelight-emitting element array cathode wiring pattern 112F of the basemember 100 by a conductive adhesive or the like. The anode electrode 218(see FIG. 4 ) of the light-emitting element array 20 and thelight-emitting element array anode wiring patterns 111-1F and 111-2F areconnected by the bonding wires 23A and 23B.

The cathode electrode of the PD 40 is bonded onto the PD cathode wiringpattern 114F of the base member 100 by a conductive adhesive, and theanode electrode of the PD 40 is connected to the PD anode wiring pattern113F of the base member 100 by the bonding wire 23C. Further, oneterminal of the TD 45 (a positive terminal in a case where the TD 45 haspolarity) is bonded to the TD anode wiring pattern 115F of the basemember 100 by a conductive adhesive or solder, and the other terminal ofthe TD 45 (a negative terminal in a case where the TD 45 has polarity)is bonded to the TD cathode wiring pattern 116F of the base member 100by a conductive adhesive or solder.

As described above, in the light-emitting device 4 according to thepresent exemplary embodiment, the TD 45 having a small occupation areais provided between the light-emitting element array 20 and the driveunit 50 among the PD 40 and the TD 45 that are desired to be disposedclose to the light-emitting element array 20, so that it is easy tobring the drive unit 50 and the light-emitting element array 20 close toeach other. Since the base member 100 is used, even in a configurationin which the TD 45 is disposed between the light-emitting element array20 and the drive unit 50, a wiring pattern (here, the light-emittingelement array cathode wiring pattern 12) that connects the drive unit 50and the light-emitting element array 20 is linearly provided withoutbeing affected by the TD 45. Accordingly, an increase in the inductanceof the circuit is prevented.

In the light-emitting device 4 according to the present exemplaryembodiment, the TD 45 having a small occupation area on the base member100 is provided between the light-emitting element array 20 and thedrive unit 50 among the PD 40 and the TD 45 that are desired to bedisposed close to the light-emitting element array 20, so that it iseasy to bring the drive unit 50 and the light-emitting element array 20close to each other. Hereinafter, a light-emitting device 4′ to whichthe present exemplary embodiment is not applied will be described forcomparison.

(Light Emitting Device 4′ According to Comparative Example)

FIG. 9 is a plan view showing the light-emitting device 4′ forcomparison to which the present exemplary embodiment is not applied.

In the light-emitting device 4′, the PD 40 having a large occupationarea on the base member 100 is provided between the light-emittingelement array 20 and the drive unit 50. That is, positions where the PD40 and the TD 45 are disposed in the light-emitting device 4 shown inFIGS. 7(a) to 7(c) are switched in the light-emitting device 4′. Otherconfigurations are the same as those of the light-emitting device 4, anddescription thereof will be omitted.

In the light-emitting device 4′, since the PD 40 having a largeoccupation area is provided between the light-emitting element array 20and the drive unit 50, the distance D2 between the end portion of thelight-emitting element array 20 at the drive unit 50 side and the driveunit 50 is larger than the distance D1 of the light-emitting device 4(D2>D1). That is, since the occupation area of the PD 40 is large, it isdifficult to bring the drive unit 50 and the light-emitting elementarray 20 close to each other.

As described above, the PD 40 occupies a larger area on the base member100 than the TD 45. Alternatively, when the PD 40 occupies a smallerarea on the base member 100 than the TD 45, the PD 40 may be providedbetween the drive unit 50 and the light-emitting element array 20. Thatis, when there are plural circuit elements desired to be disposed closeto the light-emitting element array 20, a circuit element having a smalloccupation area on the base member 100 may be provided between the driveunit 50 and the light-emitting element array 20. Accordingly, it is easyto bring the drive unit 50 and the light-emitting element array 20 closeto each other. Therefore, an increase in the inductance of the circuitis prevented.

Although the light receiving element for monitoring a light amount(PD40) is described as an example of the first circuit element, and thetemperature detecting element (TD45) is described as an example of thesecond circuit element in the present exemplary embodiment, othercircuit components such as the capacitor 70 that supplies a current tothe light-emitting element array 20 may be used as a circuit element.

Although the light diffusing member 30 is used in the present exemplaryembodiment, the present invention may be applied to a configurationincluding a member that transmits light, for example, a transparent basemember such as a protective cover, and an optical member such as acondensing lens or a microlens array, instead of the light diffusingmember 30.

The foregoing description of the embodiments of the present inventionhas been provided for the purposes of illustration and description. Itis not intended to be exhaustive or to limit the invention to theprecise forms disclosed. Obviously, many modifications and variationswill be apparent to practitioners skilled in the art. The embodimentswere chosen and described in order to best explain the principles of theinvention and its practical applications, thereby enabling othersskilled in the art to understand the invention for various embodimentsand with the various modifications as are suited to the particular usecontemplated. It is intended that the scope of the invention defined bythe following claims and their equivalents.

REFERENCE SIGNS LIST

-   1 information processing device-   2 user interface (UI) unit-   3 optical device-   4, 4′ light-emitting device-   5 3D sensor-   6 resistor element-   7, 70 capacitor-   8 optical device control unit-   9 system control unit-   10 substrate-   11-1, 11-2, 111-1F, 111-2F, 111-1B, 111-2B light-emitting element    array anode wiring pattern-   12, 112F, 112B light-emitting element array cathode wiring pattern-   13, 113F, 113B PD anode wiring pattern-   14, 114F, 114B PD cathode wiring pattern-   15, 115F, 115B TD anode wiring pattern-   16, 116F, 116B TD cathode wiring pattern-   20 light-emitting element array-   21A, 21B, 22A, 22B side surface-   23A, 23B, 23C bonding wire-   30 light diffusing member-   40 PD (light receiving element for monitoring light amount)-   45 TD (temperature detecting element)-   50 drive unit-   51 MOS transistor-   52 signal generation circuit-   60 holding unit-   61A, 61B, 62A, 62B wall-   81 shape specifying unit-   82 power source-   83 power source line-   84 ground line-   91 authentication processing unit-   100 base member-   200 semiconductor substrate-   202 lower DBR-   206 active region-   208 upper DBR-   210 current confinement layer-   210A oxidized region-   210B conductive region-   214 cathode electrode-   218 anode electrode-   M mesa-   VCSEL vertical cavity surface emitting laser element

The invention claimed is:
 1. A light-emitting device comprising: awiring substrate; a base member provided on the wiring substrate; alight-emitting element array that has a first side surface and a secondside surface facing each other, that has a third side surface and afourth side surface facing each other and connecting the first sidesurface and the second side surface, and that is provided on the basemember; a drive unit that is provided on the wiring substrate at a sideof the first side surface and drives the light-emitting element array; afirst circuit element that is provided on the base member at the side ofthe first side surface; a second circuit element that is provided on thebase member at a side of the second side surface and has a largeroccupation area on the base member than the first circuit element; andwiring members that are provided at a side of the third side surface andat a side of the fourth side surface and extend from an upper surfaceelectrode of the light-emitting element array toward an outer side ofthe light-emitting element array.
 2. The light-emitting device accordingto claim 1, wherein at least one of the first circuit element and thesecond circuit element is a light receiving element that receives lightemitted from the light-emitting element array.
 3. The light-emittingdevice according to claim 1, wherein at least one of the first circuitelement and the second circuit element is a temperature detectingelement that detects a temperature of the base member.
 4. Thelight-emitting device according to claim 1, wherein one of the firstcircuit element and the second circuit element is a temperaturedetecting element that detects a temperature of the base member, andother of the first circuit element and the second circuit element is alight receiving element that receives light emitted from thelight-emitting element array.
 5. The light-emitting device according toclaim 1, wherein the wiring members that extend from the upper surfaceelectrode of the light-emitting element array toward the outer side ofthe light-emitting element array are not provided between the first sidesurface and the first circuit element and between the second sidesurface and the second circuit element.
 6. The light-emitting deviceaccording to claim 2, wherein the wiring members that extend from theupper surface electrode of the light-emitting element array toward theouter side of the light-emitting element array are not provided betweenthe first side surface and the first circuit element and between thesecond side surface and the second circuit element.
 7. Thelight-emitting device according to claim 3, wherein the wiring membersthat extend from the upper surface electrode of the light-emittingelement array toward the outer side of the light-emitting element arrayare not provided between the first side surface and the first circuitelement and between the second side surface and the second circuitelement.
 8. The light-emitting device according to claim 4, wherein thewiring members that extend from the upper surface electrode of thelight-emitting element array toward the outer side of the light-emittingelement array are not provided between the first side surface and thefirst circuit element and between the second side surface and the secondcircuit element.
 9. The light-emitting device according to claim 1,wherein a light diffusing member that diffuses light emitted from thelight-emitting element array toward an outer side is provided on anemission path of the light-emitting element array.
 10. Thelight-emitting device according to claim 2, wherein a light diffusingmember that diffuses light emitted from the light-emitting element arraytoward an outer side is provided on an emission path of thelight-emitting element array.
 11. The light-emitting device according toclaim 3, wherein a light diffusing member that diffuses light emittedfrom the light-emitting element array toward an outer side is providedon an emission path of the light-emitting element array.
 12. Thelight-emitting device according to claim 4, wherein a light diffusingmember that diffuses light emitted from the light-emitting element arraytoward an outer side is provided on an emission path of thelight-emitting element array.
 13. The light-emitting device according toclaim 5, wherein a light diffusing member that diffuses light emittedfrom the light-emitting element array toward an outer side is providedon an emission path of the light-emitting element array.
 14. Thelight-emitting device according to claim 6, wherein a light diffusingmember that diffuses light emitted from the light-emitting element arraytoward an outer side is provided on an emission path of thelight-emitting element array.
 15. The light-emitting device according toclaim 9, wherein at least one of the first circuit element and thesecond circuit element is a light receiving element that receives lightemitted from the light-emitting element array, and wherein the lightdiffusing member is provided at a position overlapping thelight-emitting element array and the light receiving element in a planview.
 16. The light-emitting device according to claim 9, wherein one ofthe first circuit element and the second circuit element is a lightreceiving element that receives light emitted from the light-emittingelement array, other of the first circuit element and the second circuitelement is a circuit element other than a light receiving element, andthe light diffusing member is provided at a position that does notoverlap the circuit element other than a light receiving element andoverlaps the light-emitting element array and the light receivingelement in a plan view.
 17. The light-emitting device according to claim1, wherein the light-emitting element array includes a plurality oflight-emitting elements connected in parallel to one another.
 18. Anoptical device comprising: the light-emitting device according to claim1; and a light receiving unit that receives light emitted from thelight-emitting element array provided in the light-emitting device andreflected by an object to be measured, wherein the light receiving unitoutputs a signal corresponding to a time from when the light is emittedfrom the light-emitting element array to when the light is received bythe light receiving unit.
 19. An information processing devicecomprising: the optical device according to claim 18; and a shapespecifying unit that specifies a three-dimensional shape of the objectto be measured based on light emitted from the light-emitting elementarray provided in the optical device, reflected by the object to bemeasured, and received by the light receiving unit provided in theoptical device.
 20. The information processing device according to claim19, further comprising: an authentication processing unit that performsan authentication processing related to use of the informationprocessing device based on a specifying result of the shape specifyingunit.